If you wouldn't limit the voice of a person who owns a media outlet, why would you limit the voice of a person who just wants to buy a little piece of it?

Our constitution has a built-in capability to evolve with the times. When people wanted to outlaw alcohol, they passed an amendment (18th). A few years later when people wanted to revoke that amendment, they passed another one (21st). If you want to revoke the 1st amendment or the part of it that deals with free speech, you should convince enough people to pass a 28th amendment doing so.

One problem with your theory is that not all speech is free. You are not allowed to harm another with your speech. In this case it harms all.